Impact of neem leaves aqueous extract on the aphid predator Hippodamia variegata Goeze (Coleoptera:Coccinellidae)

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Date
2015-05-18
Authors
Ali, Maisoon Mohammed El-Tahir
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Publisher
UOFK
Abstract
This research work was carried out to study the impact of neem leaves aqueous ‎extract (NLAE) on the aphid predator Hippodamia variegata. The study was conducted under laboratory conditions at the Faculty of Agriculture, University of Khartoum. Sorghum aphid (Melanaphis sacchari) was treated with NLAE at rates of 1%, 5% and 10% to study the effect of NLAE on the feeding rate of larvae and adults of H. variegata. One percent dosage rate was relatively safe against H. variegata and was not significantly different from the control, while 5% and 10% concentrations were highly significantly different (p< 0.01) thus reducing the feeding rate of both larvae and adults. H. variegata eggs, larvae, pupae and adults were directly sprayed with NLAE at rates of 1%, 5%, and 10% and the synthetic insecticide Selecron® to study the effect of these treatments on egg hatchability, larvae and adults mortality and adults emergence rate from pupae. 1% concentration was relatively safe in relation to hatchability, larvae and adults mortality and adults emergence and was comparable to the control. The concentrations 5% and 10% in relation to hatchability, larvae and adults mortality and adults emergence were significantly different from the control (p<0.01), while Selecron® gave the highest negative effect. Results indicated that H. variegata 3rd instar larvae and pupae when treated with NLAE at rates of 1%, 5% and 10% to study the effect of NLAE on the growth of ‎larvae and emerging adults. The highest malformation rate was caused by 10% concentration followed by 5% concentration, while 1% concentration was safe, showed no malformation and comparable to the control. A recommendation was thus made that further studies should be conducted to identify the impact of neem insecticide on predators and other natural enemies, and to confirm that 1% concentration of neem leaves aqueous extract is safe to Hippodamia variegata when spraying against aphids.
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July 2005
Keywords
neem leaves
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